A variety of methods exist for tracking and providing information about items. For example, inventory items typically carry printed labels providing information such as serial numbers, price, weight, and size. Data carriers in the form of machine-readable symbols can be selected from a variety of machine-readable symbologies, such as barcode and/or area or matrix code symbologies.
Data carriers in the form of memory devices provide an alternative method for tracking and providing information about items. Memory devices permit the linking of large amounts of data with an object or item. Memory devices typically include a memory and logic in the form of an integrated circuit (IC) and means for transmitting data to and/or from the device. For example, a radio frequency identification (RFID) tag typically includes a memory for storing data, an antenna, an RF transmitter, and/or an RF receiver to transmit data, and logic for controlling the various components of the memory device. RFID tags are generally formed on a substrate and can include, for example, analog RF circuits and digital logic and memory circuits. The RFID tags can also include a number of discrete components, such as capacitors, transistors, and diodes.
RFID tags can be passive, active or hybrid devices. Active devices are self-powered, by a battery for example. Passive devices do not contain a discrete power source, but derive their energy from an RF signal used to interrogate the RFID tag. Passive RFID tags usually include an analog circuit that detects and decodes the interrogating RF signal and that provides power from the RF field to a digital circuit in the tag. The digital circuit generally executes all of the data functions of the RFID tag, such as retrieving stored data from memory and causing the analog circuit to modulate the RF signal to transmit the retrieved data. In addition to retrieving and transmitting data previously stored in the memory, the RFID tag can permit new or additional information to be stored in the RFID tag's memory, or can permit the RFID tag to manipulate data or perform some additional functions.
Another form of memory device is an optical tag. Optical tags are similar in many respects to RFID tags, but rely on an optical signal to transmit data to and/or from the tag.
A user typically secures a data carrier to an item, such as a goods, products, or containers by way of pressure-sensitive adhesives. The data carrier often encodes information specifically relating to the item such as identifying or destination information. An individual, such as a checkout or inventory clerk, can retrieve data about any given item, for example, by scanning the machine-readable symbol or interrogating the RF tag, optical tag, or touch memory device. Access to the data can be useful at the point of sale, during inventory, during transportation, or at other points in the manufacture, distribution, sale, or use of the tagged item.
Whatever the type of data carrier used, their usefulness is limited by the capability of a data collection device (such as a barcode reader, RFID reader, optical reader, and the like) to accurately read the data on the data carrier. Data collection devices are directional in nature and have limited range—such devices need to be optimally positioned in order to accurately read the data on the data carriers. If the data collection is pointed too far (or too close in some instances) to the data carrier, then the data may not be read correctly or may not be read at all. Similarly, if the data collection device is pointed askew to the data carrier, then the data may not be read or may be read incorrectly. Moreover, the data collection device may not be able to provide sufficient power to the data carrier (such as a RFID tag) if the data collection device is not optimally positioned to apply maximum power on the tag. This non-optimal positioning would inhibit both successful reading and writing. The inability of an inexperienced user to skillfully position the data collection device also contributes to the directional and range-limited liabilities of such devices, thereby further contributing to the chances of erroneous or missed data readings and/or ineffective data transfer (i.e., writing) to the data carrier.